Pieter Rossouw de Klerk (born 21 August 1989) is a South African rugby union player for the in the Pro14. His regular playing position is tighthead prop.
De Klerk began his senior career in Pretoria and made his domestic debut for the in 2009 against the . The following year he made his first Super Rugby appearance for the against the . In total he managed 33 matches for the Blue Bulls and 14 games for the Bulls.
He moved west in 2013 and played for the in the Vodacom Cup and Currie Cup competitions.
He signed for Glasgow Warriors in 2014 and won the Pro 12 title in the season 2014-15. On 31 July 2015 Glasgow Warriors announced that De Klerk would be released from his contract due to personal reasons. On 27 September 2015, Klerk signed for top French club Grenoble in the Top 14 from the 2015–2016 season.